| Abbreviation | Definition |
|---|---|
| AIGU | Airgas Specialty Gases |
| AIIZ | III Transportation |
| AIMU | TRS Containers & Chassis |
| AINX | TTX Company - Acorn Division |
| AINX | TTX Corporation Acorn Division |
| AIPX | Atlas Iron Processors |
| AIPX | Atlas Iron Processors Incorporated |
| AIR | Audit Inspection Report |
| AIRI | Alabama Industrial Railroad |
| AIRU | Air Products And Chemical |
| AIRX | American International Rail Services LLC |
| AITU | Western Intermodal |
| AITU | Western Intermodal (Arkema Rotterdam) |
| AITX | American Industrial Transport |
| AITZ | Western Intermodal |
| AJ | Alma and Jonquieres Railway |
| AJCU | Australia Japan Container Line |
| AJPX | North American Chemical |
| AJPX | North American Chemical (IMC Chemicals) |
| AJR | Artemus-Jellico Railroad |